Metal interconnections are expected to become a bottleneck of performance of electronic systems as transistors continue to scale to smaller sizes. Optical interconnections, implemented at different levels ranging from rack-to-rack down to chip-to-chip and intra-chip interconnections could enable low power dissipation, low latencies and high bandwidths. The realization of such small scale optical interconnections relies on the ability to integrate micro-optical devices with the microelectronics chip. The recent demonstrations of silicon low-loss waveguides, amplifiers and lasers advance this integrative goal, but a silicon electro-optic modulator with a size small enough for chip-scale integration is needed.